UTF8Encoding.GetByteCount Method (String)

Calculates the number of bytes that would be produced by encoding the characters in the specified String.

Namespace:  System.Text
Assembly:  mscorlib (in mscorlib.dll)

public override int GetByteCount(
	string chars


Type: System.String
The String containing the set of characters to encode.

Return Value

Type: System.Int32
The number of bytes that would be produced by encoding the specified characters.


chars is null.


The resulting number of bytes is greater than the maximum number that can be returned as an integer.


Error detection is enabled, and chars contains an invalid sequence of characters.


A fallback occurred (see Understanding Encodings for complete explanation).

To calculate the exact array size required by the GetBytes method to store the resulting bytes, call the GetByteCount method. To calculate the maximum array size, call the GetMaxByteCount method. The GetByteCount method generally allocates less memory, while the GetMaxByteCount method generally executes faster.

With error detection, an invalid sequence causes this method to throw a ArgumentException. Without error detection, invalid sequences are ignored, and no exception is thrown.


To ensure that the encoded bytes are decoded properly, the application should prefix encoded bytes with a preamble.

The following example demonstrates how to use the GetByteCount method to return the number of bytes required to encode a String using UTF8Encoding.

using System;
using System.Text;

class Example
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
      String chars = "UTF8 Encoding Example";

      UTF8Encoding utf8 = new UTF8Encoding();
      int byteCount = utf8.GetByteCount(chars);
      outputBlock.Text += String.Format(
          "{0} bytes needed to encode string.", byteCount
      ) + "\n";


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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